In its last days exploring "Cape York," a site on the rim of the giant Endeavour crater, the Opportunity rover examined a fractured rock unlike any it has seen during its nine years on Mars, researchers say.

"Water that moved through fractures during this rock's history would have provided more favorable conditions for biology than any other wet environment recorded in rocks Opportunity has seen," Opportunity principal investigator Steve Squyres, of Cornell University, said in a statement.